1. Field of the Invention
The present invention relates to a high frequency power amplifier used for amplifying high frequency signals.
2. Background Art
Japanese Laid-Open Patent Publication No. H10-335575 discloses a high frequency power amplifier in which wiring patterns (or transmission wiring patterns) are provided with resistive elements. This high frequency power amplifier also has shunt wires which shunt or short-circuit the resistive elements. The resistive elements are formed at locations substantially spaced apart from the FET chip.
An effective way to minimize oscillation in a high frequency power amplifier is to dispose a resistive element on a matching circuit substrate(s) of the amplifier so as to reduce the reflection gain. A substantial reduction in the reflection gain can be achieved by positioning this resistive element at a minimal distance from the FET chip (or field effect transistors). However, locating the resistive element in close proximity to the FET chip results in degradation in the high frequency characteristics of the high frequency power amplifier, such as the actual gain. It is, therefore, preferable to reduce the resistance value of the resistive element to minimize such degradation in the high frequency characteristics of the high frequency power amplifier.
The high frequency power amplifier disclosed in the above publication is disadvantageous in that since the resistive elements are formed at locations substantially spaced apart from the FET chip, they do not adequately suppress oscillation in the amplifier.